Oil Pan With Flow Management Tunnel

ABSTRACT

A system and method for managing return oil flow in a multiple cylinder internal combustion engine having a plurality of pistons reciprocating within corresponding cylinders of an engine block to rotate a crankshaft include an oil pan having a shallow portion and a deeper sump portion, wherein the shallow portion includes at least one tunnel extending between the shallow portion and the sump portion to block airflow generated by rotation of the crankshaft and facilitate oil flow through a localized high pressure region between the shallow portion and the sump portion.

BACKGROUND

1. Technical Field

The present disclosure relates to an internal combustion engine having an oil pan with an internal tunnel to manage oil drain-back flow and air flow.

2. Background Art

Lubrication systems for internal combustion engines that power various types of vehicles often use an oil pan with a wet sump to collect and store lubricating oil until it is recirculated through the lubricating circuits of the engine by an oil pump. Many systems rely only on the force of gravity to return oil to the sump where the pick-up tube for the oil pump is located. Packaging constraints often result in portions of the crankshaft rotating in a relatively shallow area of the oil pan. The rotation of the crankshaft, particularly at high speed, may result in windage, or oil clinging to and splashing against the crankshaft. This generally reduces available power and inhibits oil return to the sump, which may result in oil starvation, i.e. insufficient oil available to lubricate the engine. This problem has been ameliorated by the use of a windage tray, scrapers, screens, louvers, baffles, etc. and/or optimizing the oil drain-back placement to facilitate the return of a sufficient quantity of oil to the sump. One strategy for directing oil flow disclosed in DE 4139195-A1 uses air pulses from the rotating crankshaft to direct oil through a corresponding passage toward the oil pump intake.

The present disclosure recognizes another factor that may contribute to oil aeration and/or oil starvation during high speed operation. Empirical data have indicated that air pulses from the high-speed rotation/reciprocation of components within the shallow portion of the oil pan create a localized high pressure or high turbulence region. This localized high pressure region hinders the return of oil to the sump while also inhibiting crankcase gases from flowing through the high pressure region and out the PCV (positive crankcase ventilation) valve. Crankcase pressure may increase to a level that blow-by gas bubbles or percolates up through the oil drain-back channels further inhibiting oil return to the sump and potentially leading to oil starvation.

SUMMARY

A system and method for managing return oil flow and crankcase gas flow in a multiple cylinder internal combustion engine having a plurality of pistons reciprocating within corresponding cylinders of an engine block to rotate a crankshaft include an oil pan having a shallow portion and a deeper sump portion, wherein the shallow portion includes at least one tunnel extending between the shallow portion and the sump portion to block airflow generated by rotation of the crankshaft and facilitate oil flow through a localized high pressure region between the shallow portion and the sump portion.

In one embodiment, an oil pan includes a generally flat plate extending from the bottom to an adjoining side with a first lateral opening beyond the first crank pin of the crankshaft and a second lateral opening near the sump portion. In another embodiment, the tunnel is implemented by a cylinder or tube extending between the shallow portion and the sump portion of the pan. Ribs or other flow diverters may be provided on the top surface of the tunnel to direct oil flow toward the sump portion.

The present disclosure includes embodiments having various advantages. For example, the communication tunnel of the present disclosure blocks turbulent airflow that inhibits return oil flow by providing a passage for return oil flow in addition to crankcase gas flow by venting of blow-by gases through the localized high pressure region created by crankshaft rotation over the shallow portion of the pan. A communication tunnel according to the present disclosure separates the crankcase into two separate regions, which allows more aggressive scraping of a windage tray while preserving a semi-quiescent flow of oil and blow-by gases fore and aft within the tunnel.

The above advantages and other advantages and features will be readily apparent from the following detailed description of the preferred embodiments when taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a representative V-type internal combustion engine with an oil pan having a tunnel according to one embodiment the present disclosure;

FIG. 2 is a perspective view of a prototype oil pan having a tunnel formed by a generally flat plate extending from the bottom to an adjoining side according to one embodiment of the present disclosure;

FIG. 3 is a perspective/cross-sectional view illustrating an oil pan with a tunnel extending from the shallow portion to the sump portion and having ribs or deflectors for routing oil according to one embodiment of the present disclosure;

FIG. 4 is a cross-sectional view illustrating representative tunnel placement relative to a crankshaft in an internal combustion engine according to one embodiment of the present disclosure;

FIG. 5 is a plan view schematic illustrating crankcase ventilation in an oil pan with a tunnel having outer ribs to direct oil flow to a desired location according to one embodiment of the present disclosure;

FIG. 6 is an end-view schematic illustration of an oil pan and crankshaft illustrating crankcase ventilation according to one embodiment of the present disclosure;

FIG. 7 illustrates an oil pan with a plurality of communication tunnels according to one embodiment of the present disclosure; and

FIG. 8 illustrates an embodiment with a convex or partial cylindrical tunnel according to one embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

As those of ordinary skill in the art will understand, various features of the embodiments illustrated and described with reference to any one of the Figures may be combined with features illustrated in one or more other Figures to produce alternative embodiments that may not be explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. However, various combinations and modifications of the features consistent with the teachings of the present disclosure may be desired for particular applications or implementations. The representative embodiments used in the illustrations relate generally to a four-stroke, multi-cylinder, internal combustion engine with a gravity return wet sump lubrication system. Those of ordinary skill in the art may recognize similar applications or implementations with other engine/vehicle technologies.

A representative embodiment of an internal combustion engine having an oil pan with a tunnel according to the present disclosure is illustrated generally in FIG. 1. Oil pan 10 is secured to an engine or cylinder block 14 of a V-type multiple cylinder internal combustion engine, indicated generally by reference numeral 12. Cylinder block 14 includes left-hand bank 16 and right-hand bank 18 of cylinders separated by a valley 20. Engine or cylinder block 14 includes various oil lubricating passages to deliver pressurized lubricating oil to engine components, as well as gravity flow drain-back passages (not specifically illustrated) to return oil to oil pan 10. Those of ordinary skill in the art will appreciate that, although illustrated and described with reference to a four-cylinder V-type engine, the teachings of the present disclosure may be applied to other engine configurations including in-line configurations with more or fewer cylinders, for example.

Engine 12 is generally of conventional design with the exception of oil pan 10. Engine 12 includes an oil pump 22 that pumps lubricating oil from the relatively deeper sump portion 24 of oil pan 10 through an oil pick-up tube (not shown) and through oil filter 26 to pressurize various oil delivery passages in engine block 14 during engine operation. Pressurized lubricating oil is then delivered to various engine components. Gravity return passages within block 14 return oil to one or more locations within oil pan 10, which may include one or more locations in shallow portion 30 of oil pan 10.

As shown in FIG. 2, oil pan 10 includes a body generally of a single-piece stamped or cast construction having four side walls extending generally upward from a contoured bottom surface 36 to a flange 38 having holes adapted to receive fasteners for sealing attachment of oil pan 10 to engine block 14. Bottom surface 36 extends from a shallow portion 30 to a relatively deeper sump portion 24, which collects oil for intake by a pick-up tube (not shown) coupled to the oil pump 22 (FIG. 1). Bottom surface 36 may include one or more protrusions or ribs 40 generally directing oil flow toward sump portion 24.

Shallow portion 30 includes at least one tunnel 50 extending between shallow portion 30 and sump portion 24. In the embodiment illustrated in FIG. 2, tunnel 50 is implemented by a generally flat plate having a first edge secured to bottom 36 and extending from bottom surface 36 to an opposite second edge secured to an adjoining side wall of oil pan 10. The edges of the tunnel may be secured using any suitable method, such as welding for example. Alternatively, tunnel 50 may be integrally formed within pan 10. Position of tunnel 50 may vary depending upon the location of one or more oil return or drain-back passages relative to the position of the crankshaft as illustrated and described with reference to FIG. 4. Tunnel 50 is a semi-sealed cross-sectional area of some length that creates a generally enclosed region within oil pan 10 with a first lateral opening 52 spaced from front side wall 60 and a second lateral opening 54 near, or extending into sump portion 36, depending upon the particular application and implementation. Tunnel 50 allows flow from a low pressure region to a region of slightly lower pressure through a region of relatively higher pressure within oil pan 10.

Empirical data gathered by the present inventors indicated that air pulses from the rotating crankshaft, reciprocating pistons and other rotating components, particularly at higher engine speeds, created a localized high pressure region within shallow portion 30 of oil pan 10. This localized high pressure region hindered or blocked oil draining into shallow portion 30 from one or more gravity return passages from traveling toward sump portion 36. In addition, the high pressure region hindered or blocked blow-by gas from venting through the PCV valve, which instead was bubbling or percolating up through the oil return passages, further inhibiting oil return to sump portion 24. Tunnel 50 functions to block crankshaft generated air flow within the tunnel passage extending between shallow portion 30 and sump portion 24 of oil pan 10 to facilitate oil return flow through tunnel 50 to sump portion 24. As such, tunnel 50 separates the crankcase into two separate regions, which allows more aggressive scraping of any windage tray while preserving a semi-quiescent flow of oil and blow-by gases fore and aft within the tunnel. Tunnel 50 is particularly suited for applications that include a chain-drive cam system that have to drain/return oil from their lubrication systems. These cams are typically driven by a sprocket located on the front or “nose” of the crankshaft so that the systems are positioned in front of the engine such that return oil travels past the high pressure zone within the oil pan.

FIG. 3 is a perspective cross-sectional view of a representative embodiment of an oil pan with a communication tunnel having flow diverters or ribs according to the present disclosure. Oil pan 10 includes a tunnel 50′ having a plurality of generally transverse ribs 70 on a top surface, which direct oil toward a desired location within oil pan 10, such as sump portion 24. Ribs or flow diverters 70 may be oriented such that lines passing through ribs 70 intersect in a common point as illustrated in FIG. 5. Ribs or flow diverters 70 may also be positioned such that at least a portion of the ribs 70 perform a “scraping” function by being in close proximity to crankshaft 80 to remove lubricating oil clinging to the rotating crankshaft 80 (FIG. 4).

FIG. 4 is a cross-sectional view illustrating positioning of tunnel 50 with respect to crankshaft 80. Crankshaft 80 generally includes a crank pin associated with each cylinder. In the representative embodiment illustrated in FIG. 4, crankshaft 80 is associated with a four cylinder internal combustion engine and includes crank pins 82, 84, 86, and 88 that drive corresponding connecting rods and pistons (not shown). To provide a semi-quiescent flow of return oil through shallow portion 30 of oil pan 10, tunnel 50 includes a first end 52 disposed forward or past first crank pin 82, but is spaced away from the side wall of the pan so that return oil has a sufficient entrance area to tunnel 50. As described above, rotation of crankshaft 80, and particularly crank pins 82 and 84 and associated connecting rods and pistons, which are located above shallow portion 30 of pan 10, creates a localized turbulent airflow region of relatively higher pressure that may impede return oil flow toward sump portion 24. Tunnel 50 provides an enclosed region within shallow portion 30 that shields return oil from the turbulent air generated by rotation of crankshaft 80. Tunnel 50 preferably extends beyond the crank pins disposed above shallow portion 30. In the four-cylinder engine embodiment illustrated in FIG. 4, tunnel 50 preferably extends beyond first and second crank pins 82, 84, respectively, with second end or opening 54 extending into sump portion 24.

FIGS. 5 and 6 are schematics illustrating a crankcase ventilation flow path within an oil pan having a communication tunnel according to one embodiment of the present disclosure. While the use of baffles in an oil pan to manage liquid oil, particularly for management of dynamic oil surge, is relatively common, such baffles generally do not significantly affect crankcase ventilation flow. In the embodiment of FIGS. 5 and 6, however, oil pan 10′ includes a vertical baffle or separator 94 that extends generally longitudinally across the oil pan separating it into left-hand and right-hand regions to manage crankcase ventilation flow. Tunnel 50′ includes flow diverters or fins 70′ oriented such that lines passing through diverters 70′ intersect at a common point 100. Diverters 70′ direct oil flow and ventilation flow in a desired direction within oil pan 10′. Crankcase gases enter oil pan 10′ in shallow region 30 as indicated by arrow 102 and are impeded by separator 94 such that they travel in the direction generally indicated by arrow 104. Crank shaft rotation generates air flow with a portion of the airflow redirected by flow diverters 70′ generally in the direction of arrow 106 toward sump portion 24. As the ventilation airflow enters sump portion 24, it travels upward as indicated by arrows 108, 114 and is redirected by tunnel 50′ as indicated by arrow 110. Ventilation air flow exits oil pan 10′ as indicated by arrow 112 where it travels through a PCV valve to the intake. As illustrated in FIGS. 5 and 6, tunnel 50′ provides a passage for crankcase ventilation flow that is shielded from the more turbulent air flow generated by crankshaft rotation and piston reciprocation within the engine block.

FIGS. 7-8 are end-view schematic representations of alternative embodiments of an oil pan with at least one communication tunnel according to the present disclosure. FIG. 7 illustrates an embodiment having first and second tunnels 120, 122 implemented by generally flat plates extending between the bottom of the shallow portion of the pan and an adjoining side. FIG. 8 illustrates a cylindraceous tunnel 130 formed by a generally convex cylinder or portion thereof.

As the various embodiments illustrate, at least one communication tunnel disposed within the oil pan according to the teachings of the present disclosure blocks turbulent airflow that inhibits return oil flow by providing a passage for return oil flow from the shallow portion to the sump portion of the pan. In addition, the tunnel(s) facilitate positive crankcase ventilation by directing ventilation airflow through the localized high pressure region created by crankshaft rotation over the shallow portion of the pan. A communication tunnel according to the present disclosure separates the crankcase into two separate regions, which allows more aggressive scraping of oil in applications having a windage tray while preserving a semi-quiescent flow of oil and ventilation gases fore and aft in the oil pan through the tunnel.

While the best mode has been described in detail, those familiar with the art will recognize various alternative designs and embodiments within the scope of the following claims. Several embodiments have been compared and contrasted. Some embodiments have been described as providing advantages or being preferred over other embodiments in regard to one or more desired characteristics. However, as one skilled in the art is aware, different characteristics may provide advantages and be preferred in some applications while being considered less desirable or disadvantageous in other applications. These attributes include, but are not limited to: cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. As such, any embodiments described herein as being preferred or advantageous with respect to one or more characteristics do not preclude embodiments or implementations that may be less desirable or advantageous but are also within the scope of the disclosure. 

1. A multiple cylinder internal combustion engine having a plurality of pistons reciprocating within corresponding cylinders of an engine block to rotate a crankshaft, the engine comprising: an oil pan disposed generally below the crankshaft and adapted for sealing attachment to the engine block, the oil pan including a shallow portion and a deeper sump portion, wherein the shallow portion includes at least one tunnel extending between the shallow portion and the sump portion.
 2. The engine of claim 1 wherein the at least one tunnel comprises a plate extending from the bottom of the shallow portion to an adjoining side of the oil pan.
 3. The engine of claim 1 wherein the at least one tunnel has a first opening forward of a first crank pin of the crankshaft.
 4. The engine of claim 1 wherein the at least one tunnel comprises a cylinder having a first end disposed forward of a first crank pin of the crankshaft.
 5. The engine of claim 1 wherein the tunnel comprises a plurality of generally transverse ribs on a top surface to direct oil flow toward a desired location.
 6. The engine of claim 5 wherein the plurality of ribs are aligned such that lines passing through the ribs intersect at a common point.
 7. A method for managing return oil flow from a shallow portion to a sump portion of an oil pan for an internal combustion engine, the method comprising: blocking air flow generated by crankshaft rotation within a passage extending between the shallow portion and the sump portion of the oil pan.
 8. The method of claim 7 wherein the step of block air flow comprises positioning a tunnel in the oil pan with a first lateral opening in the shallow portion of the oil pan and a second lateral opening in the sump portion of the oil pan.
 9. The method of claim 8 wherein the first lateral opening is positioned forward of any crank pin of a crankshaft rotating above the oil pan.
 10. The method of claim 8 wherein the tunnel comprises a generally flat plate extending from the bottom of the oil pan to an adjacent side of the oil pan.
 11. The method of claim 10 wherein the tunnel comprises a plurality of ribs on an upper surface to direct oil toward the sump portion.
 12. The method of claim 8 wherein the tunnel comprises a cylinder having a first end disposed within the shallow portion of the oil pan and a second end disposed in the sump portion of the oil pan.
 13. An oil pan for an internal combustion engine, the oil pan comprising: a body including a bottom and four side walls, the bottom defining a shallow portion and a deeper sump portion; and a tunnel within the body extending between the shallow portion and the sump portion.
 14. The oil pan of claim 13 wherein the body comprises a one-piece metal component.
 15. The oil pan of claim 14 wherein the tunnel comprises a generally flat plate secured to the bottom along one edge and to an adjoining one of the four side walls of the body along an opposite edge.
 16. The oil pan of claim 13 wherein the tunnel extends past first and second crank pins of an associated crankshaft.
 17. The oil pan of claim 13 wherein the tunnel comprises a plurality of ribs on an upper surface to direct oil toward the sump.
 18. The oil pan of claim 17 wherein the plurality of ribs are oriented such that lines passing through the ribs intersect at a common point. 